procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

c++: Fix DMI with lambda 'this' capture [PR94205]

Browse source 
We represent 'this' in a default member initializer with a PLACEHOLDER_EXPR.
Normally in constexpr evaluation when we encounter one it refers to
ctx->ctor, but when we're creating a temporary of class type, that replaces
ctx->ctor, so a PLACEHOLDER_EXPR that refers to the type of the member being
initialized needs to be replaced before that happens.

gcc/cp/ChangeLog
2020-03-31  Jason Merrill  <jason@redhat.com>

	PR c++/94205
	* constexpr.c (cxx_eval_constant_expression) [TARGET_EXPR]: Call
	replace_placeholders.
	* typeck2.c (store_init_value): Fix arguments to
	fold_non_dependent_expr.
This commit is contained in:
Jason Merrill 2020-03-31 17:34:47 -04:00
parent 595f1b1274
commit 76f09260b7
6 changed files with 49 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
gcc/cp/ChangeLog
View file

@ -1,3 +1,11 @@
2020-03-31 Jason Merrill <jason@redhat.com>
PR c++/94205
* constexpr.c (cxx_eval_constant_expression) [TARGET_EXPR]: Call
replace_placeholders.
* typeck2.c (store_init_value): Fix arguments to
fold_non_dependent_expr.
2020-03-31 Jason Merrill <jason@redhat.com>
* constexpr.c (cxx_eval_constant_expression) [TARGET_EXPR]: Use

6
gcc/cp/constexpr.c
View file

@ -5553,6 +5553,12 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
tree init = TARGET_EXPR_INITIAL (t);
if ((AGGREGATE_TYPE_P (type) || VECTOR_TYPE_P (type)))
{
if (ctx->object)
/* If the initializer contains any PLACEHOLDER_EXPR, we need to
resolve them before we create a new CONSTRUCTOR for the
temporary. */
init = replace_placeholders (init, ctx->object);
/* We're being expanded without an explicit target, so start
initializing a new object; expansion with an explicit target
strips the TARGET_EXPR before we get here. */

2
gcc/cp/tree.c
View file

@ -3239,7 +3239,7 @@ replace_placeholders_r (tree* t, int* walk_subtrees, void* data_)
a PLACEHOLDER_EXPR has been encountered. */
tree
replace_placeholders (tree exp, tree obj, bool *seen_p)
replace_placeholders (tree exp, tree obj, bool *seen_p /*= NULL*/)
{
/* This is only relevant for C++14. */
if (cxx_dialect < cxx14)

2
gcc/cp/typeck2.c
View file

@ -871,7 +871,7 @@ store_init_value (tree decl, tree init, vec<tree, va_gc>** cleanups, int flags)
{
bool const_init;
tree oldval = value;
value = fold_non_dependent_expr (value);
value = fold_non_dependent_expr (value, tf_warning_or_error, true, decl);
if (DECL_DECLARED_CONSTEXPR_P (decl)
|| (DECL_IN_AGGR_P (decl)
&& DECL_INITIALIZED_IN_CLASS_P (decl)))

20
gcc/testsuite/g++.dg/cpp1y/constexpr-nsdmi2.C Normal file
View file

@ -0,0 +1,20 @@
// PR c++/94205
// { dg-do compile { target c++14 } }
struct S
{
struct A
{
S *p;
constexpr A(S* p): p(p) {}
constexpr operator int() { p->i = 5; return 6; }
};
int i;
int a = A(this);
};
constexpr S s = {};
#define SA(X) static_assert((X),#X)
SA(s.i == 5 && s.a == 6);

13
gcc/testsuite/g++.dg/cpp1z/lambda-this4.C Normal file
View file

@ -0,0 +1,13 @@
// PR c++/94205
// { dg-do compile { target c++17 } }
struct S
{
int i;
int a = [this] { this->i = 5; return 6; } ();
};
constexpr S s = {};
static_assert (s.i == 5 && s.a == 6);